#define  _CRT_SECURE_NO_WARNINGS
#include<stdio.h>
int main()
{
    int score = 0;
    scanf("%d", &score);
    int n = score / 10;
    switch (n)
    {
    case 10:
    case 9:
        printf("A\n");
        break;
    case 8:
        printf("B\n");
        break;
    case 7:
        printf("C\n");
        break;
    case 6:
        printf("D\n");
        break;
    case 5:
    case 4:
    case 3:
    case 2:
    case 1:
        printf("E\n");
        break;
    default:
        printf("Score is error!\n");
        break;
    }
    return 0;
}